The present invention relates to a surgical guiding instrument for a surgical machining tool, in particular, a chisel, with an implant body for insertion into an intervertebral space between adjacent vertebral bodies of the vertebral column of a human being or an animal, with a shaft and with a stop device for delimiting a depth of insertion of the implant body into the intervertebral space, the shaft having a distal end and a proximal end, the implant body being arranged at the distal end of the shaft and defining two bearing surfaces positionable against the adjacent vertebral bodies, the stop device having at least one stop movably mounted at the distal end of the shaft or on the implant body, the stop having a stop surface pointing in distal direction transversely or substantially transversely to at least one of the bearing surfaces.
Degenerative processes in the intervertebral disks articulatedly joining adjacent vertebral bodies of the vertebral column to one another are often the cause of disorders in the area of the vertebral column. In cases where the intervertebral disks have become so degenerated that they are no longer maintainable, they are often replaced by artificial intervertebral disks, so-called intervertebral implants. These can join adjacent vertebral bodies to one another rigidly or articulatedly, depending on the design of the intervertebral implant. Such intervertebral implants are often provided with fin-like projections which extend from bearing surfaces designed to bear against vertebral body surfaces adjoining the intervertebral space and prevent relative movement between the intervertebral implant and the vertebral bodies against which they bear. When introducing the intervertebral implant comprising one or two or more fin-like projections into the intervertebral space, in order to prevent damage, for example, by splitting the respective vertebral body, there are formed, for example, milled or cut with a chisel, on the vertebral bodies, prior to insertion of the intervertebral implant, grooves with which the fin-like projections of the intervertebral implant can engage. When doing so, a problem arises with the machining tool, for example, a chisel or a milling tool, being advanced ventrally too far into the intervertebral space in the direction towards the spinal canal of the spinal column. In order to avoid this, instruments are known, which comprise a stop for preventing the guiding instrument from being introduced too far into the intervertebral space, so that an insertion or cutting depth of a machining tool is delimited, more specifically, by the stop device of the instrument.
The stop devices of known instruments are arranged directly at a distal end of the instrument and can only be adjusted before the implant body of the guiding instrument is inserted into the intervertebral space. In order to vary an insertion depth or cutting depth of the surgical machining tool, the guiding instrument must be removed each time from the patient's body. Alternatively, an access to the body, which is of such size as to permit adjustment of the stop device, must be created. Minimally invasive surgery would then be virtually impossible.
The object underlying the present invention is, therefore, to so improve a surgical guiding instrument of the kind described at the outset that an insertion depth for a surgical machining tool can be set in a simple way.